European Foulbrood Disease

European foulbrood disease (EFB) is a disease of honey bees first detected in Tasmania in 1984.

It has been present in the eastern States of Australia for several years and, if left unchecked, will affect a hive to the extent that honey production will cease and the hive may die.

EFB is generally more prevalent during the spring and early summer when brood production is on the increase, but outbreaks can occur at any time during active brood rearing.

It is basically a disease of unsealed larvae. Only in severe cases do the larvae die after the cells have been sealed.

Cause

EFB results when spores of the causative bacteria (melissococcus pluton), are ingested by the larvae with their larval food and lodge in the mid-gut cavity where they multiply.

The bacteria compete with the larvae for food and starve the larvae to death. The larvae usually die at 4-5 days of age and decompose rapidly.

Spread

The disease can be spread in a number of ways.

A hive can become contaminated:
  • when infected bees drift into it.
  • when healthy bees rob an infected hive.
  • when healthy bees are fed contaminated honey.
  • when watering places are contaminated with the bodies of dead bees.
Beekeepers can spread the disease from hive to hive by interchanging combs of brood and honey between infected and healthy hives.

Spread within a hive can occur when house bees clean material from infected cells. They can retain spores of the bacteria on their mouths and spread them to young larvae during feeding.

Symptoms

In the early stages of EFB infection, combs may appear normal but a close examination of individual cells may show larvae not in their normal curled position. They may give the appearance of having become restless and wandered around in the cell. Their gut line, instead of being the normal medium yellow/orange colour, may have a bleached, chalky white appearance. These white patches could be bacteria in the gut.

Larvae may die in the normal "C" shape but are often twisted into an unnatural position.

When infected they change colour from a healthy, pearly white, to yellow and through to brown. They also dry out to a loose scale that is easily removed by the house bees.

The dead larvae do not "rope out" as happens in the case of American foulbrood disease, although if tested with a matchstick, some uneven stretching of the remains may occur.

In advanced stages of the disease the brood may appear irregularly in the combs - with sick and dead larvae interspersed with those that appear healthy.

Some pupae and pre-pupae may also be dead in sealed cells and the cappings of these cells are likely to be dark, sunken and perforated.

Diagnosis and Treatment

Definite field diagnosis of EFB can be difficult. Smears and/or larval samples must be sent to a laboratory for positive identification.

It is possible to treat infected hives with antibiotics if they are not heavily infected.

In instances of heavy infection such treatment is not considered to be adequate and it is better to destroy the material.

Prevention

Some useful preventative measures for EFB are listed below:
  • Never allow bees access to honey, cappings, hive scrapings or to dirty, second-hand honey containers.
  • Never interchange combs between hives.
  • Never use second-hand material.
  • Never allow any hive to become neglected. If proper management and maintenance of the hive is no longer possible, sell it or give it away.
  • Always inspect all brood combs each spring for the presence of EFB. Early detection increases the chance of saving the hive form destruction.
  • Always sterilise the hive tool and wash the smoker, hands and/or gloves after working on a hive you may suspect to be infected. This practice is recommended when moving from hive to hive or from apiary to apiary.
EFB is a notifiable List B disease under the Animal Health Act 1995. If any beekeeper suspects that they have EFB in their hives they must notify a Department of Primary Industries, Parks, Water & Environment stock officer.

A Department stock officer will be able to assist in the diagnosis and treatment of the problem.

Contact

Co-ordinator - Apiary Biosecurity
Karla Williams
13 St Johns Avenue
New Town TAS 7008
Phone: (03) 6165 3778
Mobile: 0407 436 230
Email: karla.williams@dpipwe.tas.gov.au

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